Parachute release hook



April 3, 1962 s. W. cAHlLL ETAL 3,028,187

PARACHUTE RELEASE HOOK Filed Aug. l1, 1958 2 Sheets-Sheet 1 15% Z D fa` 10 S April 3, 1962 s. W.l CAI-ULL ETAL PAEACEUTE RELEASE EooK 2 Sheets-Sheet 2 Filed Aug. ll, 1958 United States Patent OP 3,028,187 PARACHUTE RELEASE HUGE Starr W. Cahill, Arcadia, and Warren W. White, Sierra Madre, Calif., assignors to Hycon Mfg. Company, Pasadena, Calif., a corporation of Delaware Filed Aug. 11, 1958, Ser. No. '754,434 1 Claim. (Cl. 294-83) Our invention relates generally to parachute hooks and more particularly to a parachute release hook which automatically releases its load immediately upon contact of the load with ground.

The purpose of parachute release hooks is to provide a means for disconnecting fthe parachute from its load as soon as the load touches ground. This prevents the parachute from dragging the load over rough terrain which may damage or cause loss of the article or material. Such releasable parachute hooks usually require a complex and bulky release mechanism or system for automatic operation. Where, however, releasable prior art hooks approached a Wieldable and reasonable size, they were found to be unreliable in operation.

It is `an object of our invention to provide a compact parachute release hook which is light in Weight but effectively strong, simple in release mechanism that requires little space, and is exceptionally reliable in operation.

Anotherobject of the invention is to provide a parachute release hook in which the release operation is initiated at the descent opening of the parachute.

A further object of our invention is to provide a parachute release hook wherein the load is positively and quickly disconnected from the hook upon contact of the load with ground.

Brietly, and in general terms, we prefer to accomplish the foregoing and other objects by providing a parachute hook assembly which includes a parachute hook for supporting Ia bail attaching a load, a spring device for normally urging the bail otf the parachute hook, a retainer block tied in position before the bail by a cord t secure the spring device under tension in a ready condition, and a reeting cutter for severing the cord to release the block and the spring device. Parachute shroud lines are attached to a thimble which is secured to the normally upper part of the parachute hook on a retaining pin, and the 4bail attaching a load is placed over the normally lower, upwardly curved part of the parachute hook after the spring device is manually pressed backwards into the ready condition. The retainer block is placed directly in fron-t of the bail and a cord is then used to tie the block in position so that the spring device cannot force the bail off the hook, or so that the bail cannot otherwise twist oft' the hook. The cord passes through the reeng cutter which is suitably mounted on the parachute hook. The firing pin of the reeiing cutter is tied to a shortened shroud line and is pulled out on descent opening of the parachute.

Our invention possesses other objects and features, some of which together with the foregoing, will be set forth in the following detailed description of a preferred embodiment of the invention. The invention will be more fully understood by reading the description with joint reference to the attached drawings, in which:

FIGURE l is a side elevational view of a preferred parachute release hook according to our invention;

FIGURE lla is -a longitudinal, sectional View of a reefing cutter;

FIGURE 2 Vis an end view of the parachute release hook of FIGURE l .taken along the line 2 2;

FIGURE 3 is another view of the parachute release hook of FIGURE l taken in the direction of arrow 3;

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FiGURE 4 is a perspective illustrating the parachute release hook; attached to a parachute and supporting a load on a bail, in an early condition before dropping of the assembly;

FIGURE 5 is a perspective similar to that of FIGURE 4 but showing the parachute release hook assembly in a condition shortly after the load is dropped and the parachute has opened; and

FlGURE 6 is another perspective which depicts the release phase of the parachute release hook at the instant that the load touches yground or the surf-ace of a body of water.

A preferred embodiment of our invention is shown in the views of FIGURES l, 2 and 3. A parachute release hook or more accurately, parachute release hook assembly, has a parachute hook 10 as its base structure. The hook l@ is preferably of fonged steel and has two spaced upright arms 10a and 10b, and a norm-ally lower, upwardly curved hook structure 10c (FIGURE l). A protruding rectangular block section 10d extends outwardly frorn the side of the hook 1l) and has a circular hole ille bored centrally over the length of the section 10d. A narrow slot lllf is cut into the section 10d in a plane which is perpendicular to the axis of the hole 10e and reaches a depth tangent to the extreme peripheral wall of the hole 10e. The slot 10)c is located at a distance below the top surface of the protruding block section 10d generally `as shown in FIGURE l. At a generally similar distance above the top surface of the block section 10d is drilled two axially aligned holes 10g and 10h in the upright arms lila and 10b, respectively. The axis of these two holes 10g and 10h is perpendicular to the central axis of hole 1de. A small tapped hole 10i is additionally made into the top surface of arm 10b, parallel with arm 10b and intersects perpendicularly with the axis of hole 10h. l

The holes ltlg and 10h accommodate the -shaft of retainer pin 12 which has a cubical end 12a and a cylindrical shaft 12b. The end of shat 12b is grooved to engage the end of a set screw 14 which is threaded into the tapped hole 1th'. `The shaft 12b mounts a thimble 16 to which parachute shroud lines are attached. The cubivcal end lZa of retainer pin l2 is also bored to provide a hole 12e which is of the same diameter as hole 10e and isV normally axially aligned with hole 16e. The holes we and 12o receive a reetng cutter 18 which has a cylindrical, tubular housing. The housing of the reeng cutter 18 is grooved 18a Vat a point `along its length generally as indicated in FIGURES l and 2, and a retaining Tru-.arc ring (not shown) is inserted between slot ltlf engaging with the groove 18a on the housing of 'reef- 'ing cutter 1S to secure the cutter 18 in place. The reefing cutter 18 is, for example, 7a type OAv-AZ-S cutter manufactured by Ordnance Associates of South Pasadena, California. The reeiing cutter 18 has a conventional tiring pin lb, la safety cotter pin 15C, and a dianietrical hole ld located near the lower end ofthe housing of the cutter 13. Y

A longitudinal sectional view of a preferred reeng cutter is shown in FIGURE la. The tubular housing H is aluminum and `can be approximately 3% inches long, have a A6 inch outer diameter and a 1A inch inside diam--A .cubical retainer block 22 and tied together.

spears? than the hole b. The shaft of tiring pin lSb forces the steel ball B into engagement with a hole lSe in the housing H as shown. The hole 13e is smaller in diameter than [the steel ball D. Another hole lc is drilled through the plunger P and is aligned with the holek through the housing H which accepts the safety cotrter pin 13C. The plunger P is hexagonal and cannot rotate in housing H. rIThe spring S is compressed bythe plunger P in the position shown. Withdrawal of the tiring pin *13b permits the steel ball B to move into the space provided by the slanting hole 17a, and the plunger P is driven downwards by the compressed spring S.

A small brass cylinder C having two channeled grooves around the sides is secured in position by knurling two (depressed) rings 18j" and 18g around the housing H. The depressed housing material internally engages the channeled grooves of the brass cylinder C. The protruding rtip of plunger P strikes a primer button C1 through a thin top cover sheet C2 and ignites a pyrotechnic type fuse C3 comprising a train of slow burning powder slugs. After a few seconds, the main powder charge C4 is detonated, blowing out a thin bottom cover sheetCS. The explosion forces gas check seal elements 19u and 19h to move downwards. Element 19a is a cup shaped piston fabricated from soft copper sheet material and element 19h is a small plastic disc. 'Ilhese elements 19a and 19'b bear against a tubular cylinder 19e which moves downwards to cut the cord that passes through the hole 18d. A cutting edge is formed at the lower end of cylinder 19al by a counter'sunk hole having 45 degree flaring walls. Movement of the cylinder 19e is stopped by the lower, inwardly -beveled end of the housing H.

A cord 20, nylon for example, is passed through the hole 18d and normally through hole 22a of a generally Onevface, the normally lower face, kof block 22 is concavely grooved ,over its length and is contoured to ride smoothly on the rounded upper :part of the curved hook structure 10c. rllhe retainer block 22 is equal in thickness to that of the kparachute hook 10 `and has ya flat normally upper face Ywhich is essentially liush with the upwardly inclined, at

topsur'face directly above the curved hook structure 10c. The'` retainer block 22 is normally held against a bail a-ttaching a load, yand the bail is braced against spring 24 VVwhich is shown in tension against cord 2), however, since 'the bail and load is omitted in FIGURES l, 2 and 3. The spring 24 is formed from a length of spring wire by bending intothe shape of a square U (see FIGURE 2) and then twisting the ends around a pivot pin Z6 which is press fitted through a hole centrally located (FIGURE l) on the parachute hook l0. The tips of the wire are then bent right angularly inwards and anchored in a small hole drilled near the bottom of arm 10b (see FIGURES l and 3). The pivot pin 26 is positioned so that the bottom of spring 24 clears the lowermost point of the curved hook structureltlc and swings in a tangential arc such that the sides of the square Uof the spring 24 force the bail and retainer block 22 in the direction that the curved hook structureltc is pointed. A small washer 2S is placed on each end of the pivot pin 26 and held in place by small Tru-arc rings 30 which engage grooves cut near the ends of the pivot pin 26.

Operation of the parachute release hook is illustrated by the sequential drawings of FIGURES 4, and 6. End `loops 32 of the parachute shroud lines are bundled Ain two parts and looped about the thimble 16 and the retainer pin l2 inserted through hole idg, the thimble 16 and hole lil/1, and set screw i4 screwed down the tapped hole i until it engages the groove at the end of the retainer pin l2. The reefing cutter 18 is next inserted through'holes 12C and Mie, and a retaining Tru-arc ring is inserted 4between slot 10j engaging the `groove 18a on the housing of-reeng cutter 18. The cord 26 is then lall weather conditions.

l passed through the hole ld and the spring 24 pulled back so that bail 34 and retainer block 22 can be slipped down over the curved hook structure lc. The cord 2li is next passed through the hole 22a in the retainer block 22 and tied firmly as shown in FIGURE 4. Finally, a string 36 is tied on one end to the tiring pin 18h and to two or three points of a shortened parachute shroud line 33 on the other end. The bail 34 attaches a load 4i) which is Vsufficiently heavy to hold spring 24 bent back in tension when the load 40 is freely suspended on its bail The safety Cotter pin 18C can be pulled prior to operational use. The, assembly is shown in substantially ready condition in FIGURE 4 for dropping.

FIGURE 5 illustrates the condition of the assembly after it is dropped and the parachute has opened. Opening of the parachute causes the shontened shroud line 38 to pull string 36 and the attached ring pin 1gb. Pullingl of the` firing pin 18b (FIGURE la) releases the small steel ball B inwardly from hole 19 which, in turn, permits spring loaded firing plunger P to strike primer button C1 and ignite the pyrotechnic type fuse C3 which provides a time delay of A6 seconds, for example, before detonating the main powder charge C4 that forces the cup shaped, tubular cylinder 19e downwards vto out the cord 20 passing through hole 18d. This time delay permits the load (and bail) to stabilize on the hook before the cord 20 is cut. The retainer block 22 is released but remains generally in position because of the upward tilt of the curved hook structure 10c. The spring 24 is held bent under tension by the relatively heavy weight of load 40 suspended on bail 34. The instant that the load 40 touches ground, the bail 34 w-ill be relievedof the weight of the load 4h. During that brief moment, the spring 24 swings Iarcuately upwards and forces the bail 34 and retainer block 22 of the `curved hook structure 10c las indicated in FIGURE 6. This actionroccurs even with a strong cross wind blowing constantly. It is noted that the retainer block 22 prevents binding of the cult cord 20 with the bail 34 during the release operation.

Thus, there is provided a comparatively small and compact parachute release hook mechanism which automattically disengages its load upon contact with the ground. The mechanism is relatively simple in structure and therefore extremely reliable in operation. Initiation of the release operation is novelly dependent upon the actual descent opening of the parachute, and accordingly an extended timing program device is unnecessary. A release structure is provided wherein the load is positively and surely disconnected from the parachute hook without binding or failure of disengagement. The mechanism can always be kept in a ready condition and is useable under Finally, but not least, a high strength hook is maintained which can support Very heavy loads.

Although some component types and vdata have been indicated in the foregoing description, specific data are given as examples only/,gend do not necessarily restrict or limit the scope of our invention. It is to be understood that the particular embodiment of the invention described above and shown in the drawings is merely illustrative `of andnot restrictive of our broad invention, and that various changes in design, structure and arrangement may be made without departing from the spirit and scope of the broader of the appended claim.

We claim:

A parachute release hook, comprising: a hook member including two normally upper, spaced upright arms, a block section protruding from one side of said hook member, and a normally lower, upwardly curved hook element forming a passageway with a lower surface of said hook member and extending from the block section side for supporting a bail attaching a load, said spaced upright arms having respective upper holes which vare axially aligned, said block section having a hole extending lengthwise therethrough, and said upwardly curved hook element having a rounded upper surface parallel to the lower surface of said hook member; a retainer pin` having an enlarged head, said retainer pin engaging the axially aligned holes in said upright arms and adapted to be attached to parachute shroud lines, the enlarged head of said retainer pin having a hole extending therethrough which is normally axially aligned with the hole in said block section; a U-shaped spring bracketing said hook member and pivoted for angular movement over the length of said curved hook element, said spring being adjustable in position against spring tension for urging the bail off said curved hook element; .a reefing cutter mounted in the axially aligned holes in said enlarged head and block section, said reefing cutter being secured in position to said hook member to provide a normally lower connection point beyond the extreme adjusted spring position; a retainer block tting between said passageway and having a coucavely grooved lower surface for riding smoothly on the rounded upper surface of said upwardly curved hook element, said retainer block being normally positioned before the bail and having Ia central opening therein; and a cord passing through the central opening of said retainer block securing said spring to said reefing cutter to prevent said `spring from forcing the bail ot said curved hook element, said reefing cutter severing said cord after energization thereof.

References Cited in the le of this patent UNITED STATES PATENTS 

